Effects of early, late and self-selected time-restricted eating on visceral adipose tissue and cardiometabolic health in participants with overweight or obesity: a randomized controlled trial

Table of Contents

Overall Summary

Study Background and Main Findings

This randomized controlled trial investigated the effects of three different time-restricted eating (TRE) schedules (early, late, and self-selected) combined with usual care (UC) versus UC alone on visceral adipose tissue (VAT) and cardiometabolic health in 197 adults with overweight or obesity over 12 weeks. No significant differences were found in VAT changes between the TRE groups and the UC group (early TRE: -4%, 95% CI -12 to 4, P = 0.87; late TRE: -6%, 95% CI -13 to 2, P = 0.31; self-selected TRE: -3%, 95% CI -11 to 5, P ≥ 0.99). However, the early TRE group showed a more pronounced reduction in subcutaneous adipose tissue (SAT) compared to the UC group (-5%, 95% CI -9 to -1, P = 0.005) and greater reductions in body weight (early TRE: -2.9 kg; late TRE: -2.4 kg; self-selected TRE: -3.1 kg). Early TRE also resulted in decreased fasting glucose and nocturnal mean glucose levels compared to the other groups. Adherence was high (85-88%) across all TRE groups, and no serious adverse events were reported.

Research Impact and Future Directions

The study provides valuable insights into the effects of different TRE schedules on body composition and cardiometabolic health. While it demonstrates that TRE can lead to weight loss and improvements in glucose homeostasis, particularly with early TRE, it also highlights the lack of significant impact on VAT reduction compared to usual care alone. Importantly, the study establishes a clear distinction between correlation and causation regarding TRE's impact on body weight and SAT. The observed changes in these parameters can be attributed to the TRE intervention due to the randomized controlled trial design. However, the lack of significant difference in VAT changes between TRE and UC groups suggests that other factors, such as overall calorie intake or adherence to the Mediterranean diet, may play a more significant role in influencing VAT.

The practical utility of these findings is that TRE, particularly early TRE, can be a useful tool for weight management and improving glucose control. The high adherence rates suggest that it is a feasible approach for individuals with overweight or obesity. However, the lack of significant VAT reduction suggests that TRE may not be the most effective strategy for targeting visceral fat specifically. These findings are consistent with previous research showing mixed results on the effects of TRE on VAT, suggesting that individual responses may vary.

While the study provides valuable guidance for practitioners, uncertainties remain. The optimal duration of TRE for maximizing health benefits is unclear, and the long-term sustainability of TRE needs further investigation. Additionally, the specific mechanisms underlying the observed effects, particularly the reduction in SAT with early TRE, require further exploration. Practitioners should consider individual patient characteristics and preferences when recommending TRE and emphasize the importance of overall dietary quality and adherence.

A critical unanswered question is whether the observed benefits of early TRE on body weight, SAT, and glucose homeostasis are sustained over the long term. Additionally, the lack of significant VAT reduction raises questions about the potential role of other factors, such as energy intake and diet composition. While the methodological limitations, including the relatively short intervention period and partially open-label design, may have affected the study's ability to detect significant differences in VAT, they do not fundamentally undermine the main conclusions regarding the positive effects of TRE on body weight and glucose homeostasis. Future research should focus on longer-term studies with larger sample sizes and fully blinded designs to address these limitations and further elucidate the role of TRE in improving metabolic health.

Critical Analysis and Recommendations

Robust Study Design (written-content)
The study employed a randomized controlled trial design - the gold standard for intervention research - which allows for strong causal inferences regarding the effects of TRE.
Section: Article
Large Sample Size (written-content)
With 197 participants, the study had a relatively large sample size, increasing statistical power and enhancing the generalizability of the findings to a broader population.
Section: Article
Comprehensive Comparison of TRE Schedules (written-content)
The study examined three different TRE schedules (early, late, and self-selected), providing valuable insights into the effects of different eating window timings and enhancing practical applicability.
Section: Article
High Adherence Rates (written-content)
The study reported high adherence rates (85-88%) across all TRE groups, suggesting that TRE is a feasible and sustainable dietary approach, even in populations with late dinner times.
Section: Article
Explore Reasons for Lack of Significant Differences in VAT Changes (written-content)
The study did not find significant differences in VAT changes between the TRE groups and the control group. Further analysis should investigate potential reasons for this, such as energy intake, baseline VAT levels, or adherence to the Mediterranean diet, to better understand the factors influencing VAT reduction.
Section: Article
Consider Longer Intervention Period (written-content)
The 12-week intervention period may have been too short to observe significant changes in VAT. Future studies should consider extending the intervention period to 6 months or longer to assess the long-term effects of TRE on VAT and cardiometabolic health.
Section: Article
Effective Data Visualization (graphical-figure)
Fig. 2 effectively uses scatter plots with overlaid means and confidence intervals to provide a clear visual representation of the data distribution and group differences, enhancing the interpretability of the results.
Section: Results
Clarity of Participant Flow (graphical-figure)
Fig. 1 clearly visualizes the participant flow through the study using a flow diagram, enhancing comprehension of the study design and improving transparency.
Section: Results
Limited Sample Size and Duration (written-content)
The study's sample size and relatively short duration may have limited the ability to detect differences in VAT and other outcomes among the intervention groups. Future studies should consider a larger sample size and a longer intervention period to better assess the effects of TRE.
Section: Discussion
Partially Open-Label Design (written-content)
Only personnel responsible for evaluating the primary outcome, other ectopic fat depots, and fasting blood samples were blinded, while others operated under an open-label approach. Future studies should consider blinding all personnel involved in the study to minimize potential bias.
Section: Discussion

Section Analysis

Article

Key Aspects

Strengths

Suggestions for Improvement

Results

Key Aspects

Strengths

Suggestions for Improvement

Non-Text Elements

Fig. 1 | Study design and participant allocation overview. Study flow diagram....
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Fig. 1 | Study design and participant allocation overview. Study flow diagram. WC, waist circumference; CVD, cardiovascular. Figure created with BioRender.com.

Figure/Table Image (Page 2)
Fig. 1 | Study design and participant allocation overview. Study flow diagram. WC, waist circumference; CVD, cardiovascular. Figure created with BioRender.com.
First Reference in Text
Overall, 14 participants (3, 2, 4 and 5 participants from the UC and early, late and self-selected TRE groups, respectively) were lost to the intervention endpoint, owing to several reasons, including work incompatibility, lack of motivation or other health or personal issues not directly related to the intervention.
Description
  • General Overview of the flow diagram: The element is a flow diagram, often used in scientific papers to illustrate the step-by-step process of a study. In this case, it shows how participants were screened, enrolled, allocated to different treatment groups, followed up, and finally, included in the analysis. Each step represents a stage in the research process, and the diagram connects these stages to show the overall flow.
  • Participant attrition: The diagram starts with the number of individuals who filled out a pre-screening questionnaire and then shows the number of participants excluded at each stage, along with the reasons for exclusion. This includes reasons like not meeting eligibility criteria, declining to participate, or being lost to follow-up. The number of participants who completed each stage is also clearly indicated.
  • Group allocation and dropouts: The diagram specifies the number of participants allocated to each of the four study groups: Usual Care (UC), Early Time-Restricted Eating (early TRE), Late Time-Restricted Eating (late TRE), and Self-Selected Time-Restricted Eating (self-selected TRE). It also indicates how many participants were lost to follow-up in each group and the reasons for dropout.
  • Definition of abbreviations: The diagram includes annotations defining abbreviations such as WC (waist circumference) and CVD (cardiovascular), ensuring the reader understands these terms within the context of the study.
  • Analysis sample sizes: The diagram visually represents the number of participants analyzed in each group, providing a clear picture of the final sample sizes used for statistical analysis. The diagram shows the numbers of women in each group, giving a breakdown of the composition of each group.
Scientific Validity
  • Adherence to CONSORT guidelines: The flow diagram accurately reflects the CONSORT guidelines for reporting randomized controlled trials, ensuring transparency in participant allocation and attrition.
  • Transparency and lack of bias: The diagram provides a clear and unbiased representation of participant flow, including reasons for exclusion and dropout, which is crucial for assessing potential selection bias.
  • Consistency with Results section: The numbers presented in the flow diagram are consistent with the participant numbers reported in the Results section, confirming the accuracy of the data.
  • Assessment of internal validity: By visually showing the attrition rate in each arm, the diagram aids in assessing the study's internal validity and the potential impact of participant dropout on the results.
Communication
  • Clarity of participant flow: The figure's flow diagram clearly visualizes the participant flow through the study, enhancing comprehension of the study design.
  • Visual appeal: The use of BioRender.com allows for a professional and visually appealing diagram, improving engagement.
  • Definition of abbreviations: Abbreviations are defined in the caption, aiding quick understanding.
Table 1 | Baseline characteristics of participants by intervention group
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Table 1 | Baseline characteristics of participants by intervention group
First Reference in Text
The participant baseline characteristics are shown in Table 1.
Description
  • Overview of characteristics: Table 1 presents the characteristics of the participants at the beginning of the study, before any intervention was applied. These characteristics are split into several categories: demographics (like age and sex), anthropometry (measurements of the body, like weight, height, and BMI), abdominal adipose tissue (visceral, subcutaneous, and intermuscular fat), body composition (fat-free mass, appendicular lean mass, fat mass, and fat mass percentage), blood pressure, glucose homeostasis (fasting glucose, insulin, HOMA-IR, HbA1c, 24h mean glucose, diurnal mean glucose, nocturnal mean glucose, and CV of glucose levels), blood lipid profile (total cholesterol, HDL-C, LDL-C, triglycerides, APOA1, and APOB), and dietary intake (energy intake).
  • Descriptive statistics: For each characteristic, the table shows the average (mean) or middle value (median) for each of the four intervention groups: Usual Care (UC), Early Time-Restricted Eating (Early TRE), Late Time-Restricted Eating (Late TRE), and Self-Selected Time-Restricted Eating (Self-Selected TRE). For characteristics that vary normally, the table provides the standard deviation (a measure of how spread out the data is). For characteristics that do not vary normally, the table provides the first and third quartiles (the 25th and 75th percentiles, indicating the range within which the middle 50% of the data falls).
  • Glucose homeostasis measures: The table includes several measures of glucose homeostasis, which are related to how the body regulates blood sugar. Key measures include: fasting glucose (blood sugar levels after a period of not eating), insulin (a hormone that helps glucose enter cells), HOMA-IR (Homeostatic Model Assessment for Insulin Resistance, an estimate of insulin resistance), HbA1c (glycated hemoglobin, a measure of average blood sugar levels over the past 2-3 months), 24h mean glucose (average glucose level over 24 hours), diurnal mean glucose (average glucose during the day), nocturnal mean glucose (average glucose during the night), and CV glucose (coefficient of variation of glucose levels, a measure of glucose variability).
  • Abdominal adipose tissue: The table presents data on abdominal adipose tissue, which refers to fat stored in the abdominal region. It includes measurements of visceral fat (fat surrounding the internal organs), subcutaneous fat (fat located under the skin), and intermuscular fat (fat located between the muscles). These measures are provided in cubic centimeters (cm³).
  • Blood Pressure: The table includes blood pressure (BP) data, which are measurements of the force exerted by circulating blood on the walls of blood vessels. Systolic blood pressure (the pressure when the heart beats) and diastolic blood pressure (the pressure when the heart is at rest between beats) are provided in millimeters of mercury (mm Hg).
Scientific Validity
  • Importance of baseline characteristics: The inclusion of baseline characteristics is essential for assessing the comparability of the intervention groups at the start of the study, which is a critical aspect of randomized controlled trials.
  • Comprehensive variable selection: The table includes a comprehensive set of relevant variables, covering demographics, anthropometry, body composition, glucose homeostasis, blood lipid profile, and dietary intake, providing a holistic view of the participants' health status.
  • Appropriate statistical measures: The use of appropriate descriptive statistics (mean and standard deviation for normally distributed variables, median and quartiles for non-normally distributed variables) ensures accurate representation of the data.
  • Assessment of confounding variables: By presenting these baseline characteristics, the table allows for the assessment of potential confounding variables and helps in interpreting the study results.
Communication
  • Comprehensive overview: The table effectively presents a comprehensive overview of the baseline characteristics, enabling readers to assess the comparability of the intervention groups.
  • Appropriate descriptive statistics: The use of standard deviations and quartiles provides a clear understanding of the data distribution for both normally and non-normally distributed variables.
  • Organization and clarity: The table is well-organized, with clear headings and subheadings that facilitate easy navigation and data retrieval.
Fig. 2 | Changes in VAT, body weight and composition after intervention. a-e,...
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Fig. 2 | Changes in VAT, body weight and composition after intervention. a-e, Changes in VAT volume (a), VAT percentage (b), body weight (c), fat-free mass (d) and fat mass (e) among the UC, early TRE, late TRE and self-selected TRE groups after the 12 week intervention.

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Fig. 2 | Changes in VAT, body weight and composition after intervention. a-e, Changes in VAT volume (a), VAT percentage (b), body weight (c), fat-free mass (d) and fat mass (e) among the UC, early TRE, late TRE and self-selected TRE groups after the 12 week intervention.
First Reference in Text
The decrease in body weight was significantly greater in the early TRE group (mean difference: -2.9 kg; 95% CI, -4.7 to -1.1; P<0.001), late TRE group (mean difference: -2.4 kg; 95% CI, -4.2 to -0.6; P=0.004) and self-selected TRE group (mean difference: -3.1 kg; 95% CI, -4.9 to-1.2; P < 0.001) compared with the UC group (Fig. 2 and Table 2).
Description
  • Overview of the Figure: Fig. 2 presents the changes in visceral adipose tissue (VAT), body weight, and body composition after a 12-week intervention period in four groups: Usual Care (UC), Early Time-Restricted Eating (early TRE), Late Time-Restricted Eating (late TRE), and Self-Selected Time-Restricted Eating (self-selected TRE). The figure is divided into five subplots (a-e), each showing a different outcome variable.
  • VAT measures: Subplot (a) shows the changes in VAT volume (measured in cm³), which is a measure of the amount of visceral fat. Subplot (b) shows the changes in VAT percentage, which is the change in visceral fat relative to baseline VAT. Visceral fat is the fat stored around the abdominal organs and is associated with cardiometabolic risk.
  • Body Weight and Fat-Free Mass: Subplot (c) shows the changes in body weight (measured in kilograms), which is the total mass of an individual. Subplot (d) shows the changes in fat-free mass (measured in kilograms), which is the mass of the body excluding fat (e.g., muscle, bone, water).
  • Fat Mass and Data Representation: Subplot (e) shows the changes in fat mass (measured in kilograms), which is the total mass of fat in the body. Each subplot displays data points for individual participants, overlaid with the mean change and 95% confidence interval (CI) for each group. The 95% CI represents a range within which the true population mean is likely to fall 95% of the time.
  • Statistical Significance: The figure uses letters (a, b, c) to indicate statistically significant differences between groups, as determined by post-hoc Bonferroni correction for multiple comparisons. This means that if two groups do not share a common letter, their means are significantly different at a P < 0.05 level. Bonferroni correction is a method used to adjust the significance level when performing multiple statistical tests to reduce the risk of false positives.
Scientific Validity
  • Relevance to study objectives: The figure presents data on changes in key outcome variables related to the study's objectives, providing direct evidence for the effectiveness of the interventions.
  • Appropriate measures of uncertainty: The use of 95% confidence intervals provides a measure of the uncertainty associated with the estimated means, allowing for a more nuanced interpretation of the results.
  • Control for Type I error: The figure explicitly states that post-hoc Bonferroni correction was used for multiple comparisons, ensuring that the reported p-values are adjusted for the increased risk of Type I error.
  • Complementary to Table 2: The figure complements the information presented in Table 2, allowing for a comprehensive understanding of the study results. While the figure provides a visual representation of the data, Table 2 provides more detailed statistical information (e.g., mean differences, confidence intervals, and p-values).
Communication
  • Effective data visualization: The use of scatter plots with overlaid means and confidence intervals provides a clear visual representation of the data distribution and group differences.
  • Consistent scaling: The consistent y-axis scaling across plots facilitates comparison of the magnitude of changes in different parameters.
  • Clear indication of significance: The use of letters to denote statistically significant differences between groups, as determined by post-hoc tests, is standard and easily interpretable.
Table 2 | Changes in abdominal adipose tissue, body composition, BP, glucose...
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Table 2 | Changes in abdominal adipose tissue, body composition, BP, glucose homeostasis, blood lipid profile and dietary intake endpoints in the TRE groups compared with the UC group after the 12 week intervention

Figure/Table Image (Page 5)
Table 2 | Changes in abdominal adipose tissue, body composition, BP, glucose homeostasis, blood lipid profile and dietary intake endpoints in the TRE groups compared with the UC group after the 12 week intervention
First Reference in Text
The decrease in body weight was significantly greater in the early TRE group (mean difference: -2.9 kg; 95% CI, -4.7 to -1.1; P<0.001), late TRE group (mean difference: -2.4 kg; 95% CI, -4.2 to -0.6; P=0.004) and self-selected TRE group (mean difference: -3.1 kg; 95% CI, -4.9 to-1.2; P < 0.001) compared with the UC group (Fig. 2 and Table 2).
Description
  • Overview of the Table: Table 2 presents the changes in various health parameters after a 12-week intervention period. The table compares the changes in the Early Time-Restricted Eating (early TRE), Late Time-Restricted Eating (late TRE), and Self-Selected Time-Restricted Eating (self-selected TRE) groups to the Usual Care (UC) group. The table includes measures of abdominal adipose tissue (visceral fat, subcutaneous fat, and intermuscular fat), body composition (weight, fat-free mass, appendicular lean mass, fat mass, and fat mass percentage), blood pressure, glucose homeostasis, blood lipid profile, and dietary intake.
  • Mean Differences and Confidence Intervals: For each parameter, the table presents the mean difference between the intervention group and the UC group, along with the 95% confidence interval (CI). The mean difference indicates the average difference in the change from baseline between the intervention group and the UC group. The 95% CI provides a range within which the true population mean difference is likely to fall 95% of the time.
  • Glucose homeostasis measures: The table includes measures related to glucose homeostasis, which is how the body regulates blood sugar. Key measures include: fasting glucose (blood sugar levels after a period of not eating), insulin (a hormone that helps glucose enter cells), HOMA-IR (Homeostatic Model Assessment for Insulin Resistance, an estimate of insulin resistance), HbA1c (glycated hemoglobin, a measure of average blood sugar levels over the past 2-3 months), 24h mean glucose (average glucose level over 24 hours), diurnal mean glucose (average glucose during the day), nocturnal mean glucose (average glucose during the night), and CV glucose (coefficient of variation of glucose levels, a measure of glucose variability).
  • Blood lipid profile: The table includes blood lipid profile, which refers to the levels of different fats in the blood. Key measures include: total cholesterol (total amount of cholesterol in the blood), HDL-C (high-density lipoprotein cholesterol, often called “good” cholesterol), LDL-C (low-density lipoprotein cholesterol, often called “bad” cholesterol), triglycerides (another type of fat in the blood), APOA1 (apolipoprotein A1, a protein component of HDL), and APOB (apolipoprotein B, a protein component of LDL).
  • Dietary intake: The table includes dietary intake endpoints. Energy intake is the amount of energy (measured in kilocalories per day) that participants consumed. This provides information on whether the interventions influenced overall calorie consumption.
Scientific Validity
  • Relevance to study objectives: The table presents data on changes in key outcome variables related to the study's objectives, providing direct evidence for the effectiveness of the interventions.
  • Appropriate measures of uncertainty: The use of mean differences and 95% confidence intervals provides a measure of the uncertainty associated with the estimated effects, allowing for a more nuanced interpretation of the results.
  • Control for Type I error: The table explicitly indicates which comparisons are statistically significant, based on post-hoc tests with Bonferroni correction, ensuring that the reported p-values are adjusted for the increased risk of Type I error.
  • Detailed comparison of intervention effects: By presenting the data in a table, the authors allow for a more detailed and precise comparison of the intervention effects across different outcome variables, complementing the visual representation in Fig. 2.
  • Assessment of mediating factors: The inclusion of data on dietary intake endpoints is crucial for assessing whether the observed effects on body weight and composition are mediated by changes in energy intake.
Communication
  • Comprehensive overview of intervention effects: The table provides a comprehensive overview of the intervention effects on a wide range of outcomes, allowing for a detailed assessment of the impact of TRE on various health parameters.
  • Clear presentation of effect sizes and uncertainty: The use of mean differences and confidence intervals provides a clear understanding of the magnitude and precision of the intervention effects.
  • Organization and clarity: The table is well-organized, with clear headings and subheadings that facilitate easy navigation and data retrieval.
  • Enhancement of readability: The use of asterisks to denote statistically significant differences enhances the readability of the table and allows for quick identification of significant findings.
Table 3 | Changes in abdominal adipose tissue, body composition, BP, glucose...
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Table 3 | Changes in abdominal adipose tissue, body composition, BP, glucose homeostasis, blood lipid profile and dietary intake endpoints in the TRE groups compared with each other after the 12 week intervention

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Table 3 | Changes in abdominal adipose tissue, body composition, BP, glucose homeostasis, blood lipid profile and dietary intake endpoints in the TRE groups compared with each other after the 12 week intervention
First Reference in Text
No other significant group comparisons were observed (all P≥ 0.83; Tables 2 and 3).
Description
  • Overview of the Table: Table 3 presents the changes in various health parameters after a 12-week intervention period, focusing on comparisons between the three Time-Restricted Eating (TRE) groups: Early TRE, Late TRE, and Self-Selected TRE. Unlike Table 2, which compared each TRE group to the Usual Care (UC) group, this table directly compares the TRE groups to each other. The table includes measures of abdominal adipose tissue (visceral fat, subcutaneous fat, and intermuscular fat), body composition (weight, fat-free mass, appendicular lean mass, fat mass, and fat mass percentage), blood pressure, glucose homeostasis, blood lipid profile, and dietary intake.
  • Mean Differences and Confidence Intervals: For each parameter, the table presents the mean difference between two TRE groups, along with the 95% confidence interval (CI). For example, it shows the mean difference in the change in body weight between the Early TRE and Late TRE groups. The 95% CI provides a range within which the true population mean difference is likely to fall 95% of the time.
  • Glucose homeostasis measures: The table includes measures related to glucose homeostasis, which is how the body regulates blood sugar. Key measures include: fasting glucose (blood sugar levels after a period of not eating), insulin (a hormone that helps glucose enter cells), HOMA-IR (Homeostatic Model Assessment for Insulin Resistance, an estimate of insulin resistance), HbA1c (glycated hemoglobin, a measure of average blood sugar levels over the past 2-3 months), 24h mean glucose (average glucose level over 24 hours), diurnal mean glucose (average glucose during the day), nocturnal mean glucose (average glucose during the night), and CV glucose (coefficient of variation of glucose levels, a measure of glucose variability).
  • Blood lipid profile: The table includes blood lipid profile, which refers to the levels of different fats in the blood. Key measures include: total cholesterol (total amount of cholesterol in the blood), HDL-C (high-density lipoprotein cholesterol, often called “good” cholesterol), LDL-C (low-density lipoprotein cholesterol, often called “bad” cholesterol), triglycerides (another type of fat in the blood), APOA1 (apolipoprotein A1, a protein component of HDL), and APOB (apolipoprotein B, a protein component of LDL).
  • Dietary intake: The table includes dietary intake endpoints. Energy intake is the amount of energy (measured in kilocalories per day) that participants consumed. This provides information on whether the interventions influenced overall calorie consumption.
Scientific Validity
  • Addressing relative effectiveness: The table addresses an important question by comparing the effects of different TRE schedules directly, providing insights beyond the comparison to usual care.
  • Appropriate measures of uncertainty: The use of mean differences and 95% confidence intervals provides a measure of the uncertainty associated with the estimated effects, allowing for a more nuanced interpretation of the results.
  • Control for Type I error: The table explicitly indicates which comparisons are statistically significant, based on post-hoc tests with Bonferroni correction, ensuring that the reported p-values are adjusted for the increased risk of Type I error.
  • Assessment of timing effects: The table allows for assessment of whether the timing of the eating window (early, late, or self-selected) has a differential impact on the various health parameters.
Communication
  • Comparison of TRE groups: By presenting comparisons between the different TRE groups, the table allows for a nuanced understanding of the relative effectiveness of early, late, and self-selected TRE.
  • Presentation of effect sizes and uncertainty: The use of mean differences and confidence intervals facilitates interpretation of the magnitude and precision of the differences between the TRE groups.
  • Consistent formatting: The consistent formatting with Table 2 enhances readability and allows for easy comparison of the results.
Fig. 3 | 24 h glucose profiles before and after the intervention. a-d, Glucose...
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Fig. 3 | 24 h glucose profiles before and after the intervention. a-d, Glucose levels during 24 h as measured by CGM over 14 days in both the baseline and the last 2 weeks of the 12 week intervention for the UC (a), early TRE (b), late TRE (c) and self-selected TRE (d) groups.

Figure/Table Image (Page 8)
Fig. 3 | 24 h glucose profiles before and after the intervention. a-d, Glucose levels during 24 h as measured by CGM over 14 days in both the baseline and the last 2 weeks of the 12 week intervention for the UC (a), early TRE (b), late TRE (c) and self-selected TRE (d) groups.
First Reference in Text
Figure 3 shows the interstitial glucose levels across 24 h, tracked by continuous glucose monitoring (CGM) for 14 days at baseline and during the final 2 weeks of the 12 week intervention.
Description
  • Overview of the Figure: Fig. 3 shows the average glucose levels over a 24-hour period for each of the four study groups: Usual Care (UC), Early Time-Restricted Eating (early TRE), Late Time-Restricted Eating (late TRE), and Self-Selected Time-Restricted Eating (self-selected TRE). These glucose levels were measured using continuous glucose monitoring (CGM), a technology that tracks glucose levels in real time throughout the day and night. The figure compares glucose levels before the intervention (baseline) to glucose levels during the final two weeks of the 12-week intervention.
  • Subplot Representation: Each subplot (a-d) represents one of the study groups. The x-axis shows the time of day (in hours), and the y-axis shows the glucose level (in mg/dL). Each graph displays two lines: one representing the average glucose level at baseline and one representing the average glucose level during the final two weeks of the intervention. The shaded areas around the lines represent the 95% confidence interval (CI), which indicates the range within which the true population mean is likely to fall 95% of the time.
  • Eating Window Representation: The figure includes a visual representation of the eating window for each TRE group. This is indicated by a colored bar along the x-axis, showing the period during which participants were allowed to consume food. This helps to illustrate the relationship between meal timing and glucose fluctuations throughout the day.
  • Continuous Glucose Monitoring: Continuous glucose monitoring (CGM) involves using a small sensor inserted under the skin to measure glucose levels in the interstitial fluid (the fluid surrounding the cells). The sensor transmits data to a receiver, providing real-time glucose readings and trends. This allows for a more detailed assessment of glucose control compared to traditional blood glucose monitoring, which only captures glucose levels at specific points in time.
Scientific Validity
  • Use of CGM: The use of continuous glucose monitoring (CGM) provides a comprehensive assessment of glucose control, capturing both fasting and postprandial glucose excursions.
  • Visualization of glucose fluctuations: Presenting the data as 24-hour glucose profiles allows for a detailed visualization of the impact of TRE on glucose fluctuations throughout the day and night.
  • Comparison with baseline: Including baseline glucose profiles allows for a direct comparison of glucose control before and after the intervention, providing strong evidence for the effectiveness of TRE.
  • Quantification of uncertainty: The use of 95% confidence intervals provides a measure of the uncertainty associated with the estimated mean glucose levels, allowing for a more nuanced interpretation of the results.
Communication
  • Clarity through separate profiles: Presenting the glucose profiles for each intervention group separately enhances clarity and allows for direct comparison of the effects of each TRE schedule.
  • Contextual information: Including the eating window on the graphs provides valuable context, enabling readers to assess the relationship between meal timing and glucose fluctuations.
  • Visual representation of variability: The use of shaded areas to represent the 95% confidence interval provides a visual indication of the variability in glucose levels, improving the interpretation of the results.

Discussion

Key Aspects

Strengths

Suggestions for Improvement

Methods

Key Aspects

Strengths

Suggestions for Improvement

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